This invention relates generally to programmable pulse generators and, more specifically, to those which also have a pulse demodulating (learning) mode of operation.
An example of wide spread use of pulse generators is in the field of remote controls for television and other consumer electronic products. Unique pulse signals are electrically generated within a hand held remote control unit. These pulses are remotely communicated to the electronic equipment to be controlled by an infra-red beam. Unique infra-red pulse signals are generated for various specific control functions. One pulse signal will be generated in response to the user pressing a television channel increment button, for example, another unique pulse train for changing the sound level, as so forth. The television or other equipment receiving the pulses recognizes the function to be performed by each and executes the requested function.
The consumer electronics industry has developed without a standard set of signals for such functions. Various manufactures have their own unique set of pulse signals to remotely control various specific functions. As a result, user programmable hand held remote units have become popular. A user may program such a unit to control a number of pieces of different equipment from various manufacturers, such as a television, video tape recorder, video disc player, audio components, and the like. Programming is accomplished by directing into the hand held unit, one at a time, the various specific infra-red pulse signals that are desired to be generated by it. The unit then demodulates the signal and stores the characteristics so learned in memory. These characteristics are then used to generate a replica of the pulse train when the user later calls upon it. The heart of such a programmable hand held remote control unit is its electronic system.
An example of such an electronic system is disclosed in U.K. Patent Application No. 2,234,377, published Jan. 30, 1991. A circuit combination of counters, registers and logic are provided on an integrated circuit chip for both generating and demodulating pulse signals, under control of a central processing unit (CPU) on another integrated circuit chip. It is a primary object of the present invention to provide an improved pulse generating and demodulating system of the type there disclosed.
It is a more specific object of the present invention to provide this type of circuit with the ability to generate and demodulate signals with a reduced need for supervision and real time control by the CPU.
It is another object of the present invention to provide a pulse generating and demodulating system with greater generality and flexibility for handling a wider range of pulse modulation.
It is a further object of the present invention to provide such a pulse generating and demodulating system that, in addition to having utility in hand held remote controls, is also useful in other applications where either a programmable pulse generator and/or pulse demodulator is required.